Basic research on the fuse element pattern changing a current pathway in the process of current interruption

In recent years, power semiconductor devices are indispensable for electric power control systems. Since their operating voltage and current have been increasing more and more, the accident of the short circuit fault gives rise to the serious damage to not only the semiconductors but also the whole power control systems. Therefore, the protection techniques for the semiconductors are regarded as an important issue. This paper reports new type of etched fuse element pattern which has possibility of improving the current interruption performance. The element of etched fuse is created by chemical etching of copper plated on the ceramic substrate. This etching method enables to form fine structure of the element pattern at the current interruption points. Newly developed fuse element has the network current pathway on the ceramic substrate, and the pathway automatically changes rapidly when the short current flows. We named this fuse Intelligent Fuse. The basic design of the element of the Intelligent Fuse and the results of the interruption test are described. Two kinds of test fuse elements were prepared and the interruption tests were done under the short circuit current of about 30 kA and a recovery voltage of about 180 V. The result shows that the fault current pathway could be commutated from the ordinary current path by altering the number of the series interruption points. In addition, it is found that this commutation of the current pathway contributed to interruption of fault current.